1. Field of the Invention
Collisions with birds represent a considerable safety risk in aviation, particularly since faster aircraft have such high approaching speeds that within the prewarning time birds are unable to leave the collision area. For this reason, collisions with birds termed "bird impacts", frequently occur. A collision with one small bird does not, in general, cause great damage, although serious accidents have occurred. At sufficiently high speeds, however, and particularly with smaller jet aircraft, the impact can be so great that the body of the bird penetrates the cockpit wall or the forward edge of the wing. Cases are known in which people have been injured by bodies of birds penetrating the cabin. Particularly dramatic are collisions of commercial airlines with whole swarms of birds. Under certain circumstances, the engines may be stopped. Especially, the engines may be significantly damaged in such collisions. Large jet engines of commercial airlines produce considerable underpressure in their suction areas, which additionally increases the risk for birds in the danger zone of being sucked into the engine. The turbine blades of such engines are subjected to extremely high thermal and mechanical stresses. A bird being sucked in may, under certain circumstances, knock off a turbine blade. The immediately ensuing unbalance produces dangerous vibrations, so that the pilot must immediately shut off the affected engine. The engine turbine blade which has been knocked off can cause a great deal of damage in the interior of the engine. If the fuel feed system is damaged, the engine may catch fire. The material damages require tremendously expensive repairs, along with the aircraft out of service. Worldwide, about 200,000 bird impacts are registered every year, and the resulting damages entail costs of about 3 to 4 billion Deutsche marks. These figures alone demonstrate that a remedy is urgently needed.
2. Description of the Prior Art
Various means have previously been used to banish birds from the collision danger zone. Such measures are, for example, taking precautions to make an airport hostile to birds. Thus in many places, all trees and bushes have been removed to deprive the birds of any nesting opportunities. Furthermore, the grass on the land adjoining the runways is cut diligently as short as possible, to thereby reduce the feeding potential for the birds. Additionally grass which has been cut short allows the spotting of a swarm of birds sooner. Along with these natural measures, specially trained birds of prey may be settled on the grounds of the airport, and these birds will keep their territory free of rival birds. Various technical means have been used to chase birds away, such as for example, a stationary acoustical warning device, which cracks or blasts at irregular intervals. Also, various optical warning signals utilizing different colors, intensities, and blinking intervals have been used. All of these devices have proven to be only partially effective, but they have not been able to provide an efficient prevention of bird impacts. A cracking sound does, of course, alarm the birds, but there is no guarantee that the birds will fly away from the danger zone. Sometimes, they may even fly directly into the collision area, which they do not recognize as such due to the rapid approach of the airplane. Furthermore, a certain habituation to the sound often occurs, even if the crack or blast is emitted at irregular intervals, so that the effect is ultimately unsatisfactory in many cases.
Similar unsatisfactory results were obtained with optical warning devices. The birds soon become accustomed to all possible light colors and blinking lights. It is an object of the present invention to solve this problem and to provide a process and apparatus which effectively prevents the impact of birds with aircraft and to prevent all the negative consequences for aviation.